When some members of the enzyme family, especially the enzyme MMP9, get out of control they can promote autoimmune disease and cancer metastasis - the deadly spread of cancer around the body.

MMPs are normally held in check naturally by inhibitor molecules called TIMPs.

But the biological mechanism involved is extremely precise, and previous attempts to mimic it with artificial drugs have produced severe side effects.

The new research took a different tack by not targeting MMPs directly. Instead, tiny metallic vaccine molecules were created that fooled the immune system into manufacturing its own MMP-suppressing antibodies.

When the vaccine was tested on mice with a rodent version of Crohn's - a form of inflammatory bowel disease - it significantly reduced their symptoms.

Untreated mice suffered severe damage to their colons while those injected with the vaccine experienced only "limited" inflammation.

Professor Irit Sagi, from the Weizmann Institute in Rehovot, Israel, said: "We are excited not only by the potential of this method to treat Crohn's, but by the potential of using this approach to explore novel treatments for many other diseases."

The research is published today in the journal Nature Medicine.

At its heart is the highly selective way that TIMPs work to keep MMPs under control.

An arm on each TIMP molecule is exactly the right shape to reach an "active" site on the enzyme consisting of a combination of zinc and three peptides - protein building blocks.

"Unfortunately it is quite difficult to reproduce this precision synthetically," said Prof Sagi.

The vaccine consists of an artificial version of the zinc-peptide complex found on MMPs. This is recognised as a threat by the immune system, which produces antibodies to counter it.

The antibodies effectively copy the action of TIMPs, but far more successfully than anything manufactured in a laboratory.

Prof Sagi's team found that the antibodies - dubbed "metallobodies" - selectively targeted just two members of the MMP family, MMP2 and MMP9. They bound tightly both to mouse versions of the enzymes and human ones.

Yeda, the technology transfer arm of the Weizmann Institute, has already applied for patents on the synthetic vaccine molecules as well as the antibodies they generate.

In their paper, the scientists acknowledge the "disappointing outcomes" of man-made MMP inhibitors in previous clinical trials.

"It will be necessary to analyse potential side effects of selective anti-MMP inhibitors in the clinic," they wrote.